Heat sink for semiconductor components or similar devices, method for producing the same and tool for carrying out said method

ABSTRACT

A heat sink for semiconductor components or similar devices, especially produced from an extruded aluminum alloy. The heat sink comprises cooling ribs which rise at a distance from a base plate and which are clamped in an insert groove made in the surface of the base plate, laterally limited by longitudinal or intermediate ribs with a coupling base that has an approximately rectangular cross-section. The coupling bases are held in their insert grooves in a form-fit and are cold-welded with the base plate at least in some sections. Cross ribs extend at a distance to one another on the surfaces of the intermediate ribs and have the form of upset heels that are linked with the coupling base in a form-fit.

BACKGROUND OF THE INVENTION

The invention relates to a heat sink for semiconductor components orsimilar devices, in particular made of an extruded aluminium alloy, withcooling ribs projecting from a base plate at a spacing from one another,and each being held in a clamping manner by a coupling base which isapproximately rectangular in cross-section in an insertion groove whichis introduced into the surface of the base plate, by means oflongitudinal or intermediate ribs laterally bordering this insertiongroove. The invention also relates to a method for producing a heat sinkof this type and a tool for this.

Heat sinks of this type can be inferred from DE 25 02 472 A1; insertiongrooves of the base housing which taper conically towards the groovebase are provided for the cooling ribs on a heat sink for thyristors.These are pressed with over-dimension into the insertion grooves whichare provided with longitudinal grooves in the two side walls. While inthis case a minimum thickness of the rib is required in order to be ableto receive the necessary pressure forces in the joining method, only aninterlocking bond can be achieved in the method according to DE 35 18310 A1.

According to the teaching of this document, extruded solid profiles withlateral recesses are inserted in an interlocking manner as cooling ribsinto the insertion grooves of the separately produced base plate. Thegroove walls of the insertion groove, after insertion of the coolingrib, are formed by a tool which is wedge-like in design and can beretracted between two cooling ribs, the tool being inserted into anauxiliary groove with a V-shaped cross-section and partially pressingthe material of the housing base into parallel grooves of the coolingrib.

In both cases the insertable number of ribs—and therefore the achievableheat-dissipating surface—is limited, on the one hand, by the requiredminimum thickness of the cooling ribs and, on the other hand, by therequired minimum width of the intermediate grooves.

In light of the prior art, the inventors have set themselves the task ofdeveloping a new heat sink form and new manufacturing method, owing towhich a higher number of ribs and therefore a larger surface can beachieved with simultaneously improved heat transfer between the heatsink base and inserted cooling ribs.

SUMMARY OF THE INVENTION

The foregoing object is achieved by the present invention. According tothe invention, transverse ribs, as compression beads, extend spaced fromone another on the surfaces of the intermediate ribs on the base plateof the heat sink and abut the coupling base of cooling ribs in aninterlocking manner and improve the bond.

According to a further feature of the invention, the low intermediateribs and insertion grooves have a rectangular to slightly trapezoidalcross-section.

Within the scope of the invention is a method for producing a heat sink,in which after insertion of the cooling rib, the intermediate rib of thebase plate is formed by pressure on the rib surface thereof andtransverse ribs, as compression beads, extending on the surface of theintermediate ribs at a spacing from one another between two cooling ribsare produced and in which a transverse pressure component and a relativemovement are generated between the coupling base and the groove wallsflanking it. Owing to the press pressure exerted from above, afterinsertion of the coupling base onto the intermediate ribs, by acomparatively wide and blunt pressing edge, the intermediate ribs arethus partially formed and said compression beads are produced on theintermediate rib and rest in an interlocking manner on the couplingbase. Apart from the transverse pressure components forming during theforming process, a relative movement is achieved between the groovewalls and the coupling base which by interaction leads at leastpartially to cold weldings. After the actual pressure process, thetransverse ribs produced thereby can be again subjected to pressure andthus additionally compressed.

A tool which is designed so as to be lowerable between two cooling ribsand is equipped with a plurality of teeth which offer tooth front edgesserving as pressure faces for the intermediate ribs of the base plate atthe bottom edge of a plate-like insertion section, has provenparticularly advantageous for this method. The length of these toothfront edges preferably corresponds to the spacing of transverse ribs onthe surface of the intermediate rib. Tooth flanks which are outwardlyinclined at an acute angle issue from the tooth front edge.

It has also proved favourable for the free end of the teeth to becross-sectionally pitch circle-shaped or trapezoidal or even rectangularin design.

In a preferred configuration, the tool is produced as a spatula-liketooth plate with linear arrangement of the tooth front edges of teethprovided in a crenellated manner, wherein a side edge which is inclinedat an angle is to issue from the linear section of the tooth frontedges, at least at one end.

According to a different feature of the invention, the teeth arearranged on an insertion section of the tool plate, the cross-sectionalwidth of which is less than the spacing of the cooling ribs from oneanother and abuts a gripping section which can preferably be connectedto a whole tool. Moreover, the thickness of the gripping section is tobe greater than the spacing of the cooling ribs from one another toensure the stability in the pressure process.

In another configuration, the tool plate is to be a circular tootheddisc which rotates about a shaft and in the process machines thetangentially running heat sink.

According to the invention a tool plate with a linear bottom edge can bearranged downstream in the feed direction of the moved heat sink fromthe tool plate containing the teeth. The process sequence described bymeans of pressing with a clocked feed of the profile parts to beconnected can also be carried out in a rolling manner. In this instance,the base plate which is fitted with the cooling ribs, as a base profile,traversing a station with circular toothed discs and subsequent evendiscs.

However, it is also possible to design a tool such that the bottom edgeof the tool plate partly has teeth and is partly linear in design.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages, features and details of the invention emerge fromthe following description of preferred embodiments and with the aid ofthe drawings, in which:

FIG. 1 shows the front view of a heat sink with cooling ribs on a baseplate;

FIG. 2 shows the housing base of FIG. 1;

FIG. 3 shows a cooling rib of FIG. 1;

FIG. 4 shows a section which is enlarged relative to FIG. 1 through aregion of the heat sink;

FIG. 5 shows the plan view of the base plate;

FIG. 6 shows an enlarged detail from FIG. 5;

FIG. 7 shows the enlarged longitudinal section through FIG. 6 along itsline VII-VII;

FIG. 8 shows a side view of a pressure tool for producing the heat sink;

FIG. 9 shows a partially sectional front view of the pressure tool;

FIGS. 10, 11 shows a respective enlarged detail from FIG. 8 or 9 alongthe arrows thereof X or XI;

FIG. 12 shows a partial side view of a heat sink with a positionedpressure tool and additional tool arranged downstream;

FIG. 13 shows a side view of a different pressure tool;

FIG. 14 shows a front view of FIG. 13;

FIG. 15 shows an enlarged detail from FIG. 13 according to its arrow XV;

FIG. 16 shows the section through FIG. 15 along its line XVI-XVI;

FIGS. 17, 19 each show a detail corresponding to FIG. 10 with respect toother configurations of the pressure tool;

FIGS. 18, 20 each show a part section through FIG. 17 or 19 according tothe line thereof XVIII-XVIII or XX-XX.

DETAILED DESCRIPTION

A heat sink 10 for semiconductor components has a housing which is notshown in further detail in the drawings for reasons of clarity, with abase plate as a housing base 12 with here an exemplary width a of about120 mm and a thickness b of about 10 mm.

Insertion grooves 14 extending parallel to one another and with anapproximately rectangular cross-section with a width c of about 4 mm anda depth e of about 3 mm are formed into the base plate 12, the insertiongrooves being separated from one another by longitudinal or intermediateribs 16 which are also of rectangular cross-section with a width f whichis somewhat smaller relative to the base grooves 14. Cooling ribs 20which extend parallel to one another at a clear spacing z from oneanother are firmly located in these insertion grooves 14. The housingbase or base plate 12 and cooling ribs 20 are produced separately fromone another during extrusion from metal, in particular from aluminiumalloys, and subsequently joined.

The cooling rib 20 consists of a plate-like rib body 22, projectingfreely in the insertion position, with here a height h of about 60 mm,and a coupling base 24, of which the cross-section correspondsapproximately to that of the insertion grooves 14; in FIG. 3 the basewidth is designated c₁ and the base height e₁. Longitudinal grooves 30,separated by ribs 28, are formed into the two free end faces of the ribbody 22 of each cooling rib 20 such that the ribs 28 of the one sideface oppose the longitudinal grooves 30 of the other side face (FIG. 4).

The coupling base 24 is inserted into the insertion groove 14 of thebase plate 12 until it is located on the deepest part 15 of the groove.For better positional securing between the groove walls 17 of adjacentintermediate ribs 16, as shown in FIG. 4, each flank face of thecoupling base 24 is provided with longitudinal mouldings 26cross-sectionally producing a saw-like arrangement.

After insertion of the coupling base 24 into the insertion groove 14, aplate-like tool 40, loaded with pressure in the arrow direction P ofFIG. 8, is placed on the surface 18 of the intermediate rib 16, thebottom edge 42 of the tool 40 which is facing that surface 18 beingequipped with a crenellation-like row of teeth 44. The width i oftransverse grooves or troughs 32 in the surface 18 of the machinedlongitudinal rib 16 moreover corresponds to the length n of the toothfront edges 46 which determine that bottom edge 42; these transversetroughs 32 are produced during the exertion of the press pressure P asimpressions of those teeth 44. Tooth flanks 47 issue from their toothfront edges 46, at an angle w of about 100 to the centre line M of thetool plate 40, the tooth flanks 47 ending at inner contours 48 parallelto the tooth front edges 46 at a spacing k, with a length n₁ of the edgemouldings or tooth gaps 49 between the teeth 44.

FIG. 7 illustrates the profile of an intermediate rib 16 processed bythe tool plate 40, with transverse troughs 32 extending at spacings qfrom one another, with a width i between which transverse ribs extend ascompression beads 34, the surface of which is formed by a section of therib surface 18.

The spatula-like tool plate 40 of FIGS. 8, 12 consists of a steel platewith the width g which is divided into an upper gripping section 54,having connection holes 53 for holding screws, not shown, and with thethickness s and a lower insertion section 54 with a lesser thickness s₁.The above-mentioned centre line M of the tool plate 40 crosses thetapering region 52 between these portions 54, 56, the tool plate 40simultaneously being the straight line of symmetry; as the length g₁ ofthe mentioned bottom edge 42 corresponds to about half of the upperwidth g of the steel plates, side edges 58 inclined to the bottom edge42 at an angle w₁ of 45° issue from the two ends of the bottom edge 42,the side edges 58 abutting the upper side edges 59 of the tool plate 40extending parallel to one another, approximately half way up the heighty of the insertion section 56.

During manufacture of the heat sink 10 it is guided according to FIG. 12in the feed direction to a pressure tool 38 containing the tool plates40 located parallel to one another, the tool plates 40 reaching betweenthe cooling ribs 20 of the heat sink 10; the bottom edges 42 of the toolplates 40 are placed on the surfaces 18 of the longitudinal ribs 16 ofthe housing base or the base plate 12 and form the longitudinal ribs 16under press pressure P in the above-mentioned manner.

The less formed zones of the mentioned transverse ribs 34 produced inthe region of the tooth gaps 49 are post-formed in this example with thesmooth bottom edge 62 of a pressure plate 60 of a downstream additionaltool 64 such that an interlocking fit is produced between the groovewalls 17 and the associated flank faces of the coupling base 24.

The contour of the pressure plate 60 of the additional tool 64corresponds to the tool plate 40, as FIG. 12 shows; inclined side edges66 also issue on the tool plate 40 from the bottom edge 62 with thelength g₂, the side edges 66 passing into parallel side edges 68.

The region of the insertion section 57 located to the left of the centreline M in the tool plate 41 of FIG. 13 corresponds in design to theinsertion section 56 of the tool plate 40 (FIG. 8), the centre line Mextends into the last tooth gap 49 of this toothing towards the centre.The right-hand region of this insertion section 57 is equipped with asmooth bottom edge 62 like the pressure plate 60 of the additional tool64. This bottom edge 62 is located at a spacing k₁ from the tooth frontedges 46. The tool plates 40, 60 which are previously described withrespect to FIG. 12 are integrated here in a plate 41.

The examples of FIGS. 17, 18 and 19, 20 show that the teeth 44 _(a), 44_(b) of the tool plate 40, 41, which are also to be designated a joiningchisel, can be equipped with a cross-sectionally pitch circle-shaped endface 46 _(a) or a trapezoidal end face 46 _(b)—a possible triangulardesign is not shown.

1-17 (cancelled):
 18. A heat sink, comprising: a base plate having asurface; at least two spaced apart intermediate ribs on the surface,wherein the spaced apart intermediate ribs extend substantially parallelto each other in a longitudinal direction and define therebetween aninsertion groove; at least one cooling rib having a coupling base whichengages in the insertion groove, wherein the coupling base is held in aninterlocking manner in the insertion groove; and a plurality of spacedapart transverse ribs on the intermediate ribs, wherein the transverseribs extend substantially perpendicular to the insertion groove and abutthe coupling base of the at least one cooling rib.
 19. A heat sinkaccording to claim 18, including a plurality of spaced apartintermediate ribs defining a plurality of insertion grooves for securingthe coupling base of a plurality of cooling ribs.
 20. A heat sinkaccording to claim 18, wherein one of the coupling base and theinsertion groove has a substantially rectangular cross-section.
 21. Aheat sink according to claim 18, wherein one of the coupling base andthe insertion groove has a substantially trapezoidal cross-section. 22.A method of producing a heat sink comprising: providing a base platehaving a surface, at least two spaced apart intermediate ribs on thesurface, wherein the spaced apart intermediate ribs extend substantiallyparallel to each other in a longitudinal direction and definetherebetween an insertion groove; inserting into the insertion groove atleast one cooling rib having a coupling base which engages in theinsertion groove, wherein the coupling base is held in an interlockingmanner in the insertion groove; and thereafter forming by pressure on atop surface of the intermediate ribs a plurality of spaced aparttransverse ribs on the intermediate ribs, wherein the transverse ribsextend substantially perpendicular to the insertion groove and abut thecoupling base of the at least one cooling rib.
 23. A method according toclaim 22, including providing a plurality of spaced apart intermediateribs defining a plurality of insertion grooves for securing the couplingbase of a plurality of cooling ribs.
 24. A method according to claim 23,including providing a tool for forming the transverse ribs, the toolcomprises a plate insertion section which is insertable between twoadjoining cooling ribs, the plate insertion section includes a bottomedge having a plurality of teeth with tooth front edges serving aspressure faces for the intermediate ribs of the base plate.
 25. A methodaccording to claim 24, wherein the length (n) of the tooth front edgecorresponds to the spacing of transverse ribs on the surface of anintermediate rib.
 26. A method according to claim 25, wherein the teethhave tooth flanks which are outwardly inclined from the tooth front edgeat an acute angle (w₁).
 27. A method according to claim 24, wherein thefree end of the teeth is one of cross-sectionally pitch circle-shaped,trapezoidal, and triangular in design.
 28. A method according to claim24, wherein a spatula-like tool plate with a linear arrangement of thetooth front edges of teeth are provided in a crenellated manner.
 29. Amethod according to claim 28, wherein a side edge which are inclined atan angle (w₁) issues from the linear section of the tooth front edges,at least at one end.
 30. A method according to claim 29, wherein theteeth are arranged on one insertion section of the tool plate, of whichthe cross-sectional width (s₁) is less than the spacing (z) of thecooling ribs from one another, and is abutted by a gripping section. 31.A method according to claim 30, wherein the thickness (s) of thegripping section is greater than the spacing (z) of the cooling ribsfrom one another.
 32. A method according to claim 24, wherein the toolis a circular toothed disc.
 33. A method according to claim 24,arranging a further tool plate with a linear bottom edge downstream in afeed direction (x) of the heat sink after the tool plate containing theteeth.
 34. A method according to claim 24, wherein the bottom edge ofthe tool plate partially has teeth and is partially designed in a linearmanner.